1. Field of the Invention
The present invention concerns a method and a device for separating a predetermined number of flat objects, such as leaves stacked by a paper folder machine. In more detail, the present invention concerns the separation of paper leaves during their production and folding, to mechanically obtain packs of a predetermined number of paper napkins or the like.
The following description will refer to paper napkins by way, of example but the invention is not limited to thereto.
2. Description of the Prior Art
At present, paper napkins are produced by a paper folding machine which comprises two counter rotating rollers, a feed system and a knife.
The paper ribbon fed onto the rollers from a spool is gripped by a forceps on one of the rollers and pulled between the rollers and beyond, on the surface of said one roller, to a certain position wherein the grip of the forceps is released and the paper is left folded. A similar forceps on the other roller performs a similar operation in its turn, forming a similar folded loop on its side beyond the pair of rollers, and the process continues, depositing paper loops in turn to the left and to the right, below the area of contact with the rollers, creating a zig-zag folded ribbon. Feeders, comprising curved rods or the like, are housed in recessed grooves in the rollers and are moved out of the grooves after the formation of every loop, to distance the loops already formed in the paper ribbon from the roller, making way for new loops being folded and pushing the folded loops against a knife which cuts them in half thus forming two adjacent stacks of folded napkins.
As the above description shows, the operation up to this point is entirely mechanical and can be performed at a high production rate. The problem arises when the napkins have to be removed and sorted into packs of a fixed and pre-determined number of napkins. This stage is at present carried out manually, and the number of napkins in every pack is determined by empirical, time consuming and not very reliable methods.
There is the need for a method and a related device which allows the automation of this final part of the operation.